We have measured the e + e − → φ reaction by the K S 0 K L 0 and 3 π decay modes of the φ. We have deduced Γ ( φ → all), Γ ( φ →e + e − ), as well as B ( φ →K S 0 K L 0 ), B ( φ →K + K − ) and B ( φ → π + π − π 0 ).
No description provided.
RESONANCE FIT TO 12 DATA POINTS AROUND PHI FOR EACH CHANNEL GIVES PHI WIDTH OF 4.2 +- 0.9 MEV AND BR(PHI --> PI+ PI0 PI-/PHI --> KL KS) OF 0.667 +- 0.157 (RATHER HIGH).
No description provided.
None
RELATIVE PRODUCTION OF PION PAIRS WITHOUT RADIATIVE CORRECTIONS.
The reaction e + e − → ω o has been measured by detecting the charged pions of the π + π − π o decay mode of the ω o. A partial decay width of ω o in e + e − : Γ e + e − =0.94±0.18 keV is deduced from this result.
FITTED, BACKGROUND SUBTRACTED, PEAK OMEGA CROSS SECTION, CORRECTED FOR UNOBSERVED DECAYS, IS 1.82 +- 0.34 MUB. TABULATED ASSUMING CENTRAL ENERGY IS 782.6 MEV. VACUUM POLARIZATION AND RADIATIVE CORRECTIONS APPLIED.
The electromagnetic form factor of the pion has been determined in the ϱ o resonance region by measuring the absolute cross section of the reaction e + e − → π + π − with the Orsay storage ring. More than 800 pion pairs have been detected. The excitation curve has been fitted with a Breit-Wigner formula which leads to the following values: σ peak = (1.69 ± 0.21) 10 −30 cm 2 ; m ϱ = (770 ± 4) MeV ; Γ ϱ = (111 ± 6) MeV . The partial width of the ϱ o going into e + e − thus obtained is: Γ ϱ → e + e − =(7.36±0.7) keV .
No description provided.
We have measured the e + e − → ø reaction by its K + K − decay mode. Using our previous results on K O K O and the 3π decay mode of the ø mesons, we compute Γ ø → e + e − and then compare the whole Orsay results to theoretical predictions.
FITTED CROSS SECTIONS AT PHI PEAK. ONLY PHI --> K+ K- MEASURED HERE - ANALYSIS USES PREVIOUS EXPERIMENTS FOR OTHER CHANNELS: J.E. AUGUSTIN ET AL., PL 28B, 517 (1969).
EXCITATION OF K+ K- CHANNEL MEASURED AROUND PHI RESONANCE AT 13 ENERGIES.
We have observed a second sharp peak in the cross section for e+e−→hadrons at a center-of-mass energy of 3.695±0.004 GeV. The upper limit of the full width at half-maximum is 2.7 MeV.
No description provided.
We have measured the cross section σ for electron - positron annihilation into three or more hadrons, with at least two charged particles in the final state, at 5 GeV center-of-mass energy. We find a model-independent lower limit of σ>9.1±1.0nb; assuming invariant phase-space production of pions, we calculate the detection efficiency of our detector to be (45 ± 11)%, yielding a cross section σ=21±5nb. The average charged hadron multiplicity is found to be n¯=4.3±0.6.
No description provided.
We have measured the cross section, the distribution of scattering angles, and the distribution of noncoplanarity angles for electron-positron elastic scattering at 5 GeV c. m. energy. An analysis based on 230 events with scattering angles between 50 and 130° yields a ratio of the experimental to theoretical quantum-electrodynamic cross section of 1.03 ± 0.09. The scattering-angle and noncoplanarity-angle distributions are also found to be in excellent agreement with the quantum-electrodynamic predictions.
No description provided.
We have observed a very sharp peak in the cross section for e+e−→hadrons, e+e−, and possibly μ+μ− at a center-of-mass energy of 3.105±0.003 GeV. The upper limit to the full width at half-maximum is 1.3 MeV.
No description provided.
We present cross sections for e+e−→hadrons, e+e−, and μ+μ− near 3095 MeV. The ψ(3095) resonance is established as having an assignment JPC=1−−. The mass is 3095 ±4 MeV. The partial width to electrons is Γe=4.8±0.6 keV and the total width Γ=69±15 keV. Total rates and interference measurements for the lepton channels are in accord with μ−e universality.
No description provided.